How to specify dump name in dump_forum command?

When I call the dump_forum command and try to use the syntax listed in the admin guide I get the error:

"manage.py: error: no such option: -d
"

I want to automate a nightly/periodic backup of the forum and so far have only been able to get it to run where the script asked for a backup file name ("Please enter a filename")

This is undesirable of course for automated backups. Do I have to change the python scripts and come up woth some backup naming of my own or is there something I am missing regarding providing the backup file name at the python admin command?